It is the long range purpose of this project to study the control mechanisms important in regulating protein synthesis in normal and malignant lymphoid cells. The organization of immunoglobulin light and heavy chain genes and the control mechanisms that selecting those being transcribed and those which are expressed in protein synthesis are being studied. Particular attention is being given to the molecular genetics of IgD, since this molecule, along with IgM appears to be a very important surface component of most B lymphocytes. We have prepared a cDNA clone for mouse IgD heavy chain and are attempting to do the same for human IgD. We have discovered that mouse IgD has multiple gene segments coding for alternative carboxyl termini for IgD that either is secreted or membrane bound. At least 5 mRNAs for different form of IdG heavy chain have been identified and their structures and functions are being studied. We have prepared cDNA clones for V(L) and V(H) of galactoside-binding antibody and are characterizing its representation in the genomes of laboratory and wild mice using these cDNA clones and probes.